// 混合宏，halfborder
// 用来实现移动端1px边框

@mixin halfborder(){
	position: relative;
	&:before{
		content: '';
	    position:absolute;
	    top:-50%;
	    right:-50%;
	    bottom:-50%;
	    left:-50%;
	    @media (-webkit-min-device-pixel-ratio:1.5),(min-device-pixel-ratio:1.5){
			-webkit-transform:scale(0.7);
	    	transform:scale(0.7);
	    }
	    @media (-webkit-min-device-pixel-ratio:2),(min-device-pixel-ratio:2){
			-webkit-transform:scale(0.5);
	    	transform:scale(0.5);
	    }
	}
}